JPH074969B2 - Thermal recording material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material excellent in color development.

[Prior art]

A general heat-sensitive recording material is a colorless or light-colored coloring dye such as leuco dye as a coloring agent on a support such as paper or film, and a phenolic compound (particularly bisphenol A) as a developer for coloring the coloring when heated. , A color-forming system composed of an acidic substance such as an organic acid, and further provided with a thermosensitive color-developing layer in which a binder, a filler, a sensitivity improver, a lubricant, and other auxiliary agents are dispersed, for example, Japanese Patent Publication No. Japanese Patent Publication No.45-14039,
It was introduced in Japanese Patent Laid-Open No. 48-27736 and is widely put to practical use. This type of heat-sensitive recording sheet obtains a color image by a momentary chemical reaction between a color-developing agent and a color-developing agent during heating (a thermal printer or a Facsimile having a built-in thermal head is used for heating). Therefore, compared to other recording materials, recording can be obtained in a short time with a relatively simple device without performing complicated processing such as development and fixing, there is little noise and environmental pollution, and cost is low. Due to its advantages such as low cost, it is useful for copying books, documents and the like, and is also useful as a recording material for various information and measuring instruments such as electronic calculators, facsimiles, telex and medical measuring instruments.

On the other hand, in recent years, along with the development of society, there has been an increasing demand for high speed recording and high density recording. For this reason, it is strongly desired to develop a recording material capable of coping with the speedup of the recording apparatus itself. The first method is to lower the melting point of the electron-accepting compound as a color developer to a practically acceptable level such as storage stability (for example, 80 to 120 ° C.), and set the melting start temperature with the leuco dye. It is to lower the speed and increase the speed. However, at present, it is difficult to control the melting point of a phenolic compound which is a color developing agent which is widely used in the field of thermal recording materials, and the phenolic compound itself becomes expensive and is not practical. The second method is, for example, JP-A-53-39139 and JP-A-53-26139.
As described in JP-A No. 53-5636, JP-A No. 53-11036, etc., various waxes, fatty acid amides, alkylated biphenyls, substituted biphenyl alkanes, coumarins, etc. in the thermosensitive coloring layer. There is a method of adding a low-melting point heat-melting substance such as diphenylamines as a sensitizer (or melting point depressant). However, it is hard to say that the heat-sensitive recording materials produced by these methods are still sufficient in terms of color density, color sensitivity, background whiteness and the like.

〔Purpose〕

An object of the present invention is to provide a heat-sensitive recording material which has sufficient color density and color sensitivity, is suitable for high-speed recording, has high background whiteness, and is extremely practical.

〔Constitution〕

The heat-sensitive recording material of the present invention is a heat-sensitive recording material utilizing a color-forming reaction between a leuco dye and a color developer, and is characterized by using a dithioether compound represented by the following general formula (I) as an auxiliary component.

[In the formula, R is a hydrocarbon group having one or more unsaturated double bonds (usually having 1 to 12 carbon atoms and may have a branched chain), X and Y are hydrogen atoms or lower alkyl. Represents a group, X and Y may be the same or different, and m and n each independently represent an integer of 0 to 3. The dithioether compound represented by the general formula (I) used in the present invention may have geometric isomers of cis and trans, but there is no marked difference in action and effect caused by the difference in geometric isomers. Therefore, each may be isolated and used, or may be used as a mixture thereof.

The dithioether compound represented by the general formula (I), which is used as an auxiliary component in the present invention, contains a widely used developer (electron-accepting compound) and leuco dye (electron-donating colorless dye) when heated. By adjusting the melting point of the dithioether compound used in combination with high solubility, a heat-sensitive recording material having arbitrary sensitivity can be obtained.

The dithioether compound used in the present invention preferably has a melting point of 40 to 150 ° C., and particularly preferably 50 to 120 ° C., from the viewpoint of storage stability and sensitivity as a thermosensitive recording material. Specific examples of the dithioether compound of the present invention are shown below,
The present invention is not limited to these.

The leuco dyes used in the present invention may be used alone or as a mixture of two or more, and as such leuco dyes,
What has been applied to this type of heat-sensitive material is arbitrarily applied, for example, triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, indolinophthalide-based dye leuco compounds are preferably used . Specific examples of such leuco dyes include those shown below.

3,3-bis (p-dimethylaminophenyl) -phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet red lactone), 3,3-bis ( p-dimethylaminophenyl) -6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-dimethylaminophenyl) phthalide, 3-cyclohexylamino- 6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane , 3-diethylamino-6-methyl-7-chlorofluorane, 3- (Np-tolyl-N-ethylamino) -6-methyl- -Anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- {N- (3'-trifluoromethylphenyl) amino} -6-diethylaminofluorane, 2- {3,6 -Bis (diethylamino) -9- (o-chloroanilino) xanthylbenzoic acid lactam}, 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) fluorane, 3-diethylamino-7- (o-chloroanilino) Fluorane, 3-dibutylamino-7- (o-chloroanilino) fluorane, 3-N-methyl-N-isoamylamino-6-methyl-
7-anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3- (N, N -Diethylamino) -5-methyl-7- (N, N
-Dibenzylamino) fluorane, benzoyl leuco methylene blue 6'-chloro-8'-methoxy-benzoindolino-pyrrillospirane, 6'-promo 3'-methoxy-benzoindolino-pyrrolispirane, 3- (2'-hydroxy-4 ′ -Dimethylaminophenyl) -3- (2′-methoxy-5′-chlorophenyl)
Phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-nitrophenyl)
Phthalide, 3- (2'-hydroxy-4'-diethylaminophenyl-3- (2'-methoxy-5'-methylphenyl) phthalide, 3- (2'-methoxy-4'-dimethylaminophenyl) -3- (2'-hydroxy-4'-chloro-5'-
Methylphenyl) phthalide, 3-morpholino-7- (N-propyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7- (N -Benzyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7- (di-p-chlorophenyl) methylaminofluorane, 3-diethylamino-5-chloro-7- (α-phenylethylamino) fluorane, 3 -(N-ethyl-p-toluidino) -7- (α-phenylethylamino) fluorane, 3-diethylamino-7- (o-methoxycarbonylphenylamino) fluorane, 3-diethylamino-5-methyl-7- (α -Phenylethylamino) fluorane, 3-diethylamino-7-piperidi Fluoran, 2-chloro-3-(N-Mechirutoruijino)-7-(p
-N-butylanilino) fluorane, 3- (N-benzyl-N-cyclohexylamino)-
5,6-benzo-7-α-naphthylamino-4′-bromofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-N-ethyl-N- (2-ethoxypropyl) amino -6-Methyl-7-anilinofluorane, 3-N-ethyl-N-tetrahydrofurfurylamino-
6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-mesitidino-
4 ', 5'-benzofluorane and the like.

As the developer used in the present invention, various electron-accepting compounds, for example, phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof, are preferably applied. Here is an example:

4,4'-isopropylidene bisphenol, 4,4'-isopropylidene bis (o-methylphenol), 4,4'-secondary butylidene bisphenol 4,4'-
Isopropylidene bis (2-tert-butylphenol), 4,4'-cyclohexylidene diphenol, 4,4'-isopropylidene bis (2-chlorophenol), 2,2'-methylenebis (4-methyl-6-tert-phenyl) Butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis (6-tertbutyl-2methyl)
Phenol, 4,4'-thiobis (6-tertbutyl-2-methyl) phenol, 4,4'-diphenol sulfone, 4,4'-diphenol fluphoxide, isopropyl p-hydroxybenzoate, p-fudroxy Benzyl benzoate, benzyl protocatechuate, stearyl gallate, lauryl gallate, octyl gallate, 1,7-bis (4-hydroxyphenylthio) -3,5-dioxaheptane, 1,5-bis (4-hydroxyphenyl) Thio) -3-oxapentane, 1,3-bis (4-hydroxyphenylthio) -propane, 1,3-bis (4-hydroxyphenylthio) -2-hydroxypropane, N, N′-diphenylthiourea, N, N′-di (m-chlorophenyl) thiourea, salicylanilide, 5-chloro-salicylanilide, salicyl-o-chloroanilide, 2-hydroxy-3-naphthoic acid, 2-hydroxy-1-naphthoic acid, 1-hydroxy-2-naphthoic acid, metal salts of hydroxynaphthoic acid such as zinc, aluminum and calcium.

In the present invention, in order to support the leuco dye, the color developer and the auxiliary component on the support, various conventional binders can be appropriately used, and examples thereof include polyvinyl alcohol, starch and its derivatives, Cellulose derivatives such as methoxy cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic acid amide / acrylic acid ester copolymer, acrylic acid amide / acrylic acid ester / methacrylic acid ternary copolymer Combined, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate,
Water-soluble polymers such as gelatin and casein, polyvinyl acetate, polyurethane, styrene / butadiene copolymer,
Polyacrylic acid, polyacrylic acid ester, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer, styrene / butadiene /
A latex such as an acrylic copolymer can be used.

Further, in the present invention, together with the leuco dye, the color developer, and the auxiliary component, if necessary, further, an auxiliary additive component commonly used in this type of heat-sensitive recording material, for example, a filler, a surfactant, a heat-fusible component It is possible to use together a volatile substance (or a lubricant) and the like. In this case, as the filler, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, inorganic fine powder such as surface-treated calcium or silica, etc. ,
Examples include organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin.

The heat-sensitive recording material of the present invention is produced, for example, by applying a heat-sensitive coating liquid containing the above-mentioned components on a suitable support such as paper, synthetic paper, plastic film, and drying. In this case, the leuco dye, the color developer, and the color-sensitivity increasing agent are appropriately used in amounts of 5 to 40% by weight, 20 to 60% by weight, and 20 to 60% by weight, respectively.

〔effect〕

The heat-sensitive recording material of the present invention has improved sensitivity, is suitable for high-speed recording, has high background whiteness, and is extremely practical.

〔Example〕

Next, the present invention will be described in more detail with reference to examples. The parts and% shown below are based on weight.

Example 1 [Liquid A] 3- (N-methyl-N-cyclohexylamino) -6-
Methyl-7-anilinofluoran 20 parts 10% aqueous solution of hydroxyethyl cellulose 20〃water 60〃 [solution B] Bisphenol A 20 parts 10% aqueous solution of hydroxyethylcellulose 20〃water 60〃 [solution C] 1,4-bis (Phenylthio) -trans-2-butene 20
Parts (compound of compound example No. 5, melting point 77 to 78 ° C.) 5% aqueous solution of methylcellulose 20 parts water 60 〃 [solution D] calcium carbonate 20 parts methylcellulose 5% aqueous solution 20 〃 water 60 〃 then solution 10 parts B 30 parts of solution, 30 parts of solution C, 20 parts of solution D and 10 parts of 20% aqueous solution of isobutylene-maleic anhydride copolymer were mixed to prepare a thermosensitive color forming layer forming solution having a basis weight of 50
After coating and drying on a quality paper of g / m ^{2 so} that the dry adhesion amount becomes 4 to 5 g / m ² , a thermosensitive coloring layer is provided, and then the surface of the layer is further adjusted so that the surface smoothness becomes 500 to 600 seconds. A thermosensitive recording material (a) was prepared by calendering.

Example 2 A thermosensitive recording material (b) was prepared in the same manner as in Example 1 except that the following solution [E] was used instead of the solution [B] in Example 1.

[E] Liquid p-Hydroxybenzoic acid benzyl ester 20 parts 10% aqueous solution of hydroxyethyl cellulose 20 parts Water 60 〃 Example 3 All except that the following [F] liquid was used instead of the [B] liquid of Example 1. Thermal recording material (c) as in Example 1
It was created.

[F liquid]

1,7-Bis (4-hydroxyphenylthio) -3,5-dioxaheptane 20 parts 10% aqueous solution of hydroxyethyl cellulose 20〃water 60〃 Example 4 Instead of [C liquid] of Example 1, the following [H The same procedure as in Example 1 except that the liquid] was used.
It was created.

[H liquid]

1,4-bis (3,4-dimethylphenylthio) -trans-
2-butene (compound of compound example No. 14, melting point 82-84
C.) 20 parts 5% aqueous solution of methyl cellulose 20 parts water 60 parts Comparative Example 1 Example 1 except that water was used instead of the [C] solution of Example 1.
A heat-sensitive recording material (e) was prepared in the same manner as.

Comparative Example 2 A thermosensitive recording material (f) was prepared in the same manner as in Example 2 except that water was used instead of the liquid [C] of Example 2.

Comparative Example 3 A thermosensitive recording material (g) was prepared in the same manner as in Example 3 except that water was used instead of the liquid [C] of Example 3.

Comparative Example 4 A thermosensitive recording material (h) was prepared in the same manner as in Example 1 except that the following liquid [G] was used instead of the liquid [C] in Example 1.

[G] Liquid 20 parts of stearic acid amide 5% aqueous solution of methylcellulose 20〃 water 60〃 Comparative Example 5 The same as Example 2 except that the above [G] liquid was used in place of the [C] liquid of Example 2. A thermal recording material (i) was prepared.

Comparative Example 6 A thermosensitive recording material (j) was obtained in the same manner as in Example 3 except that the above [G] solution was used instead of the [C] solution in Example 3.

The thermal recording materials (a) to (j) obtained as described above are
Matsushita Electronic Parts Co., Ltd. thermal printing test equipment with thin film head, head power 0.45W / dot, 1 line recording time 20
The pulse width was printed at 1.6, 2.0, and 2.4 (msec) under the conditions of msec /, scanning line density 8 × 3.85 dots / mm, and the print density was measured with a Macbeth densitometer RD-514 (filter-W-106). . The results are shown in Table-1.

Next, the thermal recording materials (a) to (j) were dried under the condition of 60 ° C.
A 24-hour storability test was conducted to examine changes in background density. The results are shown in Table-2.

From the above results, it can be seen that the heat-sensitive recording material of the present invention has a high color-developing sensitivity and is suitable for high-speed recording, and also has a high background whiteness and is a highly practical heat-sensitive recording material.

Claims (1)

[Claims] 1. A thermosensitive recording material utilizing a color-developing reaction between a leuco dye and a color-developing agent thereof, as a supplementary component, a compound represented by the general formula: (In the formula, R represents a hydrocarbon group having at least one unsaturated double bond, X and Y represent a hydrogen atom or a lower alkyl group, and X represents
And Y may be the same or different, and m and n each independently represent an integer of 0 to 3) in combination with a dithioether compound.